Minor changes

detection_events
- output data.table or tibble object if input is either of those and
data.frame otherwise
- faster (e.g., 11 sec vs 31 sec for 7.2M records on wimpy laptop)
- coerce 'time_sep' argument to numeric if quoted and error if it cannot
be coerced to numeric

crw_in_polygon

changed sampling algorithm to mimimize stuck-at-boundary errors

added option to input SpatialPolygons object

added explicit coordinate reference system (EPSG 3175 - Great Lakes
projected CRS) so that default units are in meters and simulations are
done in that CRS. Other CRS can be specified for other areas (via
EPSG argument).

added option to return spatial object or simple data frame.

transmit_along_path

added option to input SpatialPolygons object

added explicit coordinate reference system (EPSG 3175 - Great Lakes
projected CRS) so that default units are in meters and simulations are
done in that CRS. Other CRS can be specified for other areas (via
EPSG argument).

added option to return spatial object or simple data frame.

detect_transmissions

added option to input SpatialPolygons object

added explicit coordinate reference system (EPSG 3175 - Great Lakes
projected CRS) so that default units are in meters and simulations are
done in that CRS. Other CRS can be specified for other areas (via
EPSG argument).